The separation and further treatment of crude oil fractions into the numerous products that are used by the industrial world comprises one of the world's largest industries. In general, the processing of crude oil into the many end products needed by modern society is referred to as the petroleum refining and petrochemical businesses. Most often, the objective of the crude separation and treatment steps involved in these businesses is to ultimately provide hydrocarbon products having particular characteristics, these characteristics normally being dependent on the average composition and other intrinsic compositional factors such as average molecular weight and hydrogen content of these streams.
The specific processing steps utilized in the refining and petrochemical businesses can often be carried out in a more optimal and efficient fashion if the average composition, namely the proportions of iso-paraffins, normal-paraffins, olefins, naphthenes and aromatics along with the average molecular weight and average hydrogen content of the hydrocarbon streams, being treated and/or produced, can be quickly determined such that processing conditions can be regulated and modified to produce the most desirable products. Also, it is often economically desirable to select or blend available hydrocarbon streams based on their average composition and characteristics to produce a more optimum and valuable product.
The measurement of the average composition and characteristics of hydrocarbon mixtures is often difficult and time consuming, with the difficulty and time required for such measurement increasing drastically for hydrocarbon mixtures boiling above about 300 degrees Fahrenheit. While the measurement of average composition and characteristics of higher boiling hydrocarbon mixtures is possible, the time required for such measurement by normal laboratory procedures involves many hours or even days. This is a distinct problem, since many of the processes involved in these businesses utilize and produce hydrocarbon mixtures boiling either entirely or in part above 300 degrees Fahrenheit and, if the time required to measure the average composition of the feed or products is excessive, then timely control of the process to obtain the desired products is impractical or at least less efficient.
It has long been known by those skilled in the processes used for converting hydrocarbon mixtures of one composition to hydrocarbon mixtures of another composition that the final composition is most usually dependent on the initial composition as well as on the operating conditions of the particular process. Some examples of typical processes commonly used to change the composition of crude oil derived hydrocarbon mixtures in the petroleum refining and petrochemical businesses include catalytic cracking, catalytic reforming, thermal reforming, visbreaking, coking, hydrodesulphurization, isomerization, dehydrogenation, steam reforming, et al.
In any and all of these processes, as well as many others, the composition characteristics and value of the products produced are very dependent among other things, on the composition and characteristics of the hydrocarbon streams fed to the processing unit, and it would be economically advantageous to be able to quickly and readily define the average composition and characteristics of the feed and, in many cases, the products, such that the most optimum feed could be selected and the most economic operating conditions could be used.